can be reduced by elementary row operations to a matrix in reduced row echelon form. Two matrices in reduced row echelon form have the same row space if and only if they are equal. This line of reasoning also proves that every matrix is row equivalent to a unique matrix with reduced row echelon form. Additional properties Because the null space of a matrix is the orthogonal complement of the row space, two matrices are row equivalent if and only if they have the same null space. The rank of a matrix is equal to the dimension of the row space, so row equivalent matrices must have the same rank. This is equal to the number of pivots in the reduced row echelon form. A matrix is invertible if and only if it is row equivalent to the identity matrix. Matrices A and B are row equivalent if and only if there exists an invertible matrix P such that A=PB. See also Elementary row operations Row space Basis (linear algebra) Row reduction (Reduced) row echelon form References External links Linear algebra Matrices Equivalence (mathematics)